The present invention generally relates to automotive and vehicular heating systems, and more particularly, to an improved separated or connected system for continuing the heating of an automotive or vehicular interior after the engine has been turned off.
In conventional vehicular heating systems having a water-cooled engine, a hot water circulation conduit or circuit is provided which uses the heated engine coolant to provide heat to the passenger compartment of the vehicle. When the engine is operating, hot coolant from the engine is circulated through a heater core. A heater fan pushes air through the core, where it is heated by the hot engine coolant, and then into the passenger compartment. Accordingly, in these conventional heating systems, it was necessary to leave the engine idling, even when the vehicle was stationary or unoccupied, in order to keep a vehicle's passenger compartment warm. Only with the engine idling could hot coolant be pumped through the heater core. Such excessive idling causes unnecessary fuel consumption and air pollution.
In order to prevent such excessive idling, after-run heaters have been developed for continuing the heating of vehicle interiors even after the engine is turned off. After-run heaters utilize much of the coolant heat by transferring it into the passenger compartment. An example of such a heater is shown in Perhats, U.S. Pat. No. 4,308,994, the disclosure of which is incorporated herein by reference. A magnetically-coupled pump with low battery drain, along with auxiliary control components, is utilized to circulate the still-hot engine coolant through the vehicle's heater core and to run the vehicle's heater fan while the engine is off.
Those skilled in the art will recognize that systems of the type shown in the U.S. Pat. No. 4,308,994 require the interconnection between components located within the passenger compartment and components located within the engine compartment. More specifically, components such as the seasonal switch, indicator and fan motor controls are located in the passenger compartment inside or under the dash, whereas the engine coolant pump and temperature sensor are located in the engine compartment. The interconnection of these components requires the installing of wiring through the firewall between the two compartments. The wiring may pass through the firewall. This type of system is referred to herein as an interconnected system. Those skilled in the art will recognize that, depending on the specific configuration of the vehicle's firewall, engine compartment and dash, installation of an interconnected system can prove to be time-consuming, difficult, and therefore very costly.
These problems were addressed in the after-run heater of Perhats, U.S. Pat. No. 6,116,552, the disclosure of which is incorporated herein by reference. A pump and first control circuit therefore are located in the engine compartment of the vehicle. The first control circuit allows the pump to continue circulating heated engine coolant through the heater core of the vehicle after the engine has been turned off. A second control circuit, located in the passenger compartment of the vehicle, continues to operate the heater fan which blows air through the heater core and into the passenger compartment after the engine has been turned off. The first and second control circuits have no mechanical, electrical or electromagnetic interconnection therebetween but nevertheless are interrelated and codependent. This type of system is referred to herein as a divided system.
Those skilled in the art will recognize that installation of after-run heating systems involves a broad range of vehicles sizes, types and styles. Accordingly, the system and its installation can prove to be costly due to the required specificity in manufacture, distribution and inventory for each vehicle. Furthermore, in some vehicles the arrangement of the heating system, firewall and related components renders installation of the interconnected after-run heating system relatively straightforward. That is, there is no need for the divided system of the U.S. Pat. No. 6,116,552. In other vehicles it can range from difficult to impossible to install the interconnected system of the U.S. Pat. No. 4,308,994. In such vehicles the divided after-run heating system of the U.S. Pat. No. 6,116,552 is required.